GB2160176A

GB2160176A - Ribbon cassette for typewriters or other printing machines

Info

Publication number: GB2160176A
Application number: GB08428389A
Authority: GB
Inventors: Norbert Hofmann
Original assignee: TA Triumph Adler AG
Current assignee: TA Triumph Adler AG
Priority date: 1984-06-08
Filing date: 1984-11-09
Publication date: 1985-12-18
Also published as: IT1213226B; US4605325A; JPH0449480B2; GB8428389D0; CH663760A5; GB2160176B; JPS60264273A; DE3421407C1; IT8423222A0

Description

1

SPECIFICATION

Ribbon cassette for typewriters or other printing machines This invention relates to a ribbon cassette for a typewriter or other printing machine in which cassette the ribbon is provided in a roll wound on a rotatably mounted delivery spool. With such rib- bon cassettes, it has proved necessary to secure the roll on the delivery spool so that it cannot be displaced axially on the spool since such axial displacement of the roll leads to the formation of a tapered roll which is likely to rub on other structures of the cassette thus hindering smooth unwinding of the ribbon during operation. Spools which have flanges at both sides of the roll will prevent axial displacmeent of the roll, but cannot be considered for certain cassettes in which the roll of ribbon on the take-up spool comes within range of the delivery spool as the diameter of the former increases, or for those cassettes where the take- up spool moves towards the delivery spool during use. In both cases the delivery spool flanges would inter- fere with the cassette operation.

German Utility Model No. 80 32 607 discloses the use of a slide which is intended to secure the roll of ribbon against axial displacement prior to the use of the ribbon cassette. In this case, it is a disadvantage that the ribbon cassette does not work properly if - as has often been observed - it is forgotten to remove the slide before fitting the cassette in the printing machine. As a result, frictional forces result which cannot easily be overcome by the ribbon drive.

It is an object of the present invention to provide a ribbon cassette in which the roll of ribbon on the delivery spool is secured against axial displacement when the cassette is not inserted in the type- writer or other printing machine with which it is intended to be used and in which the means so securing the roll are rendered inoperative when the cassette is inserted in the printing machine.

According to the invention there is provided a ribbon cassette for a typewriter or other printing machine, comprising a roll of ribbon on a delivery spool which supports one side of the roll, and a retaining member biased into engagement with the other side of the roll to prevent axial displacement of the roll on the spool, said retaining member being adapted to be caused to be moved axially out of engagement with said other side of the roll against said bias to a non-roll engaging position, by engagement of the cassette with a release member of a printing machine with which the cassette is intended to be used, when the cassette is fitted in the machine.

Preferably, the retaining member is arranged to be acted on directly by the release member of the printing machine when the cassette is fitted in the 125 machine.

Advantageously, the spoof is mounted for rotation on a spindle and the retaining member is nonrotatably mounted on said spindle, the retaining member being arranged to engage said spool to GB 2 160 176 A 1 prevent its rotation on said spindle when said retaining member is in its biased position and to be out of engagement with said spool when said retaining member is its non-roll engaging position.

This feature thereby prevents unwanted rotation of the delivery spool as well as axial displacement of the roll thereon when the cassette is not inserted in a printing machine.

In a preferred embodiment, to be described hereinafter, the retaining member and spool are provided with respective teeth which engage when the retaining member is in its biased position to secure the spool against rotation relative to the re taining member.

Also in the embodiment the spindle is hollow, is connected to, and extends from, the base plate of the cassette, and is snap fitted to a formation de pending from the cover plate of the cassette. Such an arrangement is particularly advantageous since a spring may be located in the formation depend- ing from the cover plate to provide the retaining member with its bias. The formation is preferably cylindrical and thereby provides a guide for a cy lindrical spring.

The spindle may extend through a central open ing in the retaining member, a cruciform web ex tending across said central opening member and locating in corresponding longitudinal slots in the spindle to prevent rotation of the retaining mem- ber relative to the spindle.

In order that the invention may be well understood, the preferred embodiment thereof referred to above, which is given by way of example only, will now be described in more detail, with refer- ence to the accompanying drawing, in which:- Figure 1 is a cross-section through a ribbon cassette in the region of a delivery spool thereof; Figure 2 is a plan view of part of the cassette to a smaller scale than that of Figure 1 and with the cover of the cassette removed; and Figure 3 is a perspective exploded view of some individual parts of the cassette.

In Figures 1 and 2 the lower portion of a ribbon cassette is designated by 1 and comprises a base plate and peripheral side wall 2. Connected to and extending from the base plate is a spindle 3, which is hollow in construction and which rotatably mounts a delivery spool 4, on which is wound a roll of ribbon 5.

The delivery spool 4 has a flange 15 which supports one side of the roll and a retaining member 13 is biased into engagement with the other side of the roll by a cylindrical compression spring 12 to prevent axial displacement of the roll 5 on the spool 4. The retaining member 13 is automatically moved axially out of engagement with the roll 5 when the cassette is fitted in the printing machine with which it is intended to be used by means of a release pin 19 which, in the embodiment, directly engages the retaining member 13 and moves it against the bias of the spring 12 to a non-roll engaging position. In the embodiment the retaining member 13 is provided with three radially outwardly extending arms. The shape of the locking member 13 can be selected substantially as de- 2 GB 2 160 176 A 2 sired and depending on the other parts of the ribbon cassette. However, the retaining member 13 should cover a large proportion of the roll 5 of the delivery spool 4.

The shape of the spindle 3 can clearly be seen from Figure 3. A shoulder 6 serves to receive the spool 4 for rotation. Cross slots 7 in the spool spin dle 3 enable the spindle to be deformed radially in wards by a certain amount at its free end so that hook members 11 can snap-fit behind correspond ing hook members 10 on a cylindrical formation 9 depending from a cover plate 8 of the cassette when the latter is assembled. The spring 12 is hou sed within and guided by the formation 9, and is prevented from arching the cassette cover 8 out- 80 wardly.

It is also desirable that the retaining member 13 should not be able to rotate accidentally on the spindle. For this purpose the retaining member is provided, across its central opening which receives the spindle 3, with a cruciform web 14, the dimen sions of which are such that it can be inserted in the slots 7 of the spindle 3. Thus a second function of the slots 7 is to act as a means for preventing the retaining member 13 from rotating on the spin dle, whilst still allowing limited relative axial move ment between the retaining member and spindle.

Inserted between the retaining member 13 and the cover 8 and within the formation 9 is the compres sion spring 12, previously mentioned, which, when the cassette casing is assembled, ensures that the retaining member 13 is urged firmly against the roll 5 on the delivery spool 4.

As a result, the roll of ribbon is prevented from being displaced axially in the direction of the arrow A in Figure 1 even in the event of severe shaking of the cassette during transport. The flange 15 of the delivery spool 4 prevents an axial movement of the roll of ribbon 5 downwards.

Provided on the retaining member 13 there may also be teeth 16 which are in engagement with corresponding teeth 17 on the spool 4 when the retaining member 13 is in its biased, roll-engaging position. As a result, since the retaining member is non-rotatably mounted on the spindle 3 the delivery spool 4 is simultaneously secured against rotation on the spindle 3 when the cassette is not inserted in a printing machine. Thus a loop of ribbon is prevented from accidentally forming.

As usual, the ribbon cassette is placed on a cassette carrier 18 in the printing machine. The cassette can be locked in the machine by known means. Provided on the cassette carrier 18 is the release pin 19 which engages the retaining mem- ber 13 through the hollow spool spindle 3 when the cassette is placed on the cassette carrier 18 from above. This pin 19 presses against the cruck form web 14 on the retaining member 13 and lifts this, against the bias of the spring 12, sufficiently far from the roll of ribbon 5 that the teeth 16, 17 disengage to allow the spool 4 to rotate freely. Thus the action of the retaining member against axial displacement of the roll of ribbon 5 and against accidental rotation of the spool 4 is can- celled. When the cassette is removed, the spring 12 brings the retaining member 13 back into its biased, roll engaging position.

From the above description it will be appreciated that we have provided simple means for securing the roll 5 of ribbon against axial displacement without substantially increasing the cost of the cassette, which is an important consideration since the cassette is only used once and then discarded. Furthermore reliable operation of the cassette is ensured, since it does not require the intervention of the operator to release or reactuate the securing means.

Claims

1. A ribbon cassette for a typewriter or other printing machine, comprising a roll of ribbon on a delivery spool which supports one side of the roll, and a retaining member biased into engagement with the other side of the roll to prevent axial displacement of the roll on the spool, said retaining member being adapted to be caused to be moved axially out of engagement with said other side of the roll against said bias to a non-roll engaging po- sition, by engagement of the cassette with a release member of a printing machine with which the cassette is intended to be used, when the cassette is fitted in the machine.

2. A cassette as claimed in claim 1, wherein the retaining member is arranged to be acted on directly by the release member of the printing machine when the cassette is fitted in the machine.

3. A cassette as claimed in claim 1 or 2, wherein the spool is mounted for rotation on a spindle and the retaining member is non-rotatably mounted on said spindle, the retaining member being arranged to engage said spool to prevent its rotation on said spindle when said retaining member is in its biased position and to be out of en- gagement with in its biased position and to be out of engagement with said spool when said retaining member is in its non-roll engaging position.

4. A cassette as claimed in claim 3, wherein the retaining member and spool are provided with re- spective teeth which engage when the retaining member is in its biased position to secure the spool against rotation relative to the retaining member.

5. A cassette as claimed in claim 3 or 4, wherein the spindle is hollow, is connected to, and extends from, the base plate of the cassette, and is snap fitted to a formation depending from the cover plate of the cassette.

6. A cassette as claimed in claim 5, wherein a spring is located in said formation depending from the cover plate of the cassette to provide said retaining member with its bias.

7. A cassette as claimed in any one of claims 3 to 6, wherein the spindle extends through a central opening in the retaining member, a cruciform web extending across said central opening member and locating in corresponding longitudinal slots in the spindle to prevent rotation of the retaining member relative to the spindle.

3 GB 2 160 176 A 3

8. A ribbon cassette for a typewriter or other printing machine, substantially as herein described with reference to the accompanying drawings.

Printed in the UK for HMSO, D8818935, 10 85, 7102. Published by The Patent Office. 25 Southampton Buildings, London, WC2A lAY, from which copies may be obtained.